मान लीजिए $\alpha, \beta$ दो वास्तविक संख्याएँ हैं जैसे कि $\pi < (\alpha-\beta) < 3 \pi$। यदि $\sin \alpha+\sin \beta=\frac{-21}{65}$ और $\cos \alpha+\cos \beta=\frac{-27}{65}$ है,तो $\cos \left(\frac{\beta-\alpha}{2}\right)=$

  • A
    $\frac{-\sqrt{89}}{26 \sqrt{5}}$
  • B
    $\frac{-\sqrt{8}}{26 \sqrt{5}}$
  • C
    $\frac{-\sqrt{91}}{26 \sqrt{5}}$
  • D
    $\frac{-\sqrt{72}}{26 \sqrt{5}}$

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जब $\frac{\sin 9 \theta}{\cos 27 \theta}+\frac{\sin 3 \theta}{\cos 9 \theta}+\frac{\sin \theta}{\cos 3 \theta}=k(\tan 27 \theta-\tan \theta)$ परिभाषित है,तब $k=$

$\cos \frac{2 \pi}{15} \cos \frac{4 \pi}{15} \cos \frac{8 \pi}{15} \cos \frac{14 \pi}{15}$ का मान क्या है?

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$(\sec A + \tan A - 1)(\sec A - \tan A + 1) - 2\tan A = $

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